Machine tool transmissions, in particular spindle transmissions, are known from the prior art and usually comprise a planetary transmission and a shift device for shifting to the desired gear.
For example, DE 10 2004 003 684 A1 by the present Applicant describes a machine tool transmission, in particular a spindle transmission in which force or torque transmission takes place directly from the drive output shaft of the transmission to the spindle. The spindle is arranged co-axially with respect to the drive output shaft.
Further from DE 10 2004 003 685 A1 by the present Applicant, a machine tool transmission, in particular a spindle transmission is known, in which force or torque transmission takes place directly from the drive output shaft of the transmission to the spindle. The spindle is arranged co-axially with the drive output shaft. In this case, a rotary duct is integrated in the drive input shaft, which serves as a transfer device for coolant liquids, oils or air between the transmission output and the spindle.
DE 102 41 006 A1 by the present Applicant describes an electromagnetic shift device for a two-stage planetary gearset with a drive input shaft and a drive output shaft, a sun gear, a ring, gear, a planetary gear carrier with planetary gears, a transmission housing and a sliding shift sleeve for shifting to a first gear in which the ring gear can be coupled to the housing and a second gear in which the ring gear can be coupled to the sun gear, such that the sliding shift sleeve can be moved by an electromagnet consisting of magnet coils and an armature. The armature can rotate, but is axially fixed onto the sliding sleeve.
From DE 199 17 673 A1 by the present Applicant, a shift device for a two-stage planetary transmission is known. In the known planetary transmission, the drive input shaft is connected to a sun gear and the drive output shaft to a planetary gear carrier, a ring gear of the planetary transmission can be positively coupled such that a sliding shift sleeve to a transmission housing or to the sun gear and the shift sleeve can be moved co-axially with respect to the drive input shaft by way of an electric control element to the various shift positions. The control element is an electromagnet whose armature is connected to propel the shift sleeve.
Owing to their centric structure, machine tool transmissions with a space-saving planetary drive for increasing the torque are generally also suitable for high speeds. However, the designs known from the prior art limit the high speeds because in the straight-through mode (i=1:1, motor output speed=transmission output speed) the complete planetary drive with its sun gear, planetary gears, planetary gear carrier and the ring gear is driven, even though this is only necessary for producing a transmission ratio for the first gear step. In such situations, the high rotation speeds have an adverse influence on the vibration values. In addition, accelerating to maximum speed take a longer time.
For the transmission of high torques in the first gear step (i.e., with a transmission ratio), large diameters are required at the drive output, which additionally increase the rotation masses and also permit only large seal diameters. This affects the transmission temperature adversely, since the friction increases over-proportionally with diameter and speed.
The purpose of the present invention is to provide a two-stage machine tool transmission, in particular a spindle transmission for high torques and high speeds, whose vibration values are low. In addition, the temperature of the transmission should remain as low as possible.